在线升级，下载升级包过程中提示网络异常导致升级失败。
问题描述：
连接wifi，选择在线升级，在现在升级包过程中，提示网络异常，导致升级失败。
问题解决：
首先分析mainlog中对应时间点上下文的log.通过搜索rssi，查看当前wifi连接状态，如下：
12-03 15:49:37.523602: E/WifiManager(812): calculateSignalLevel rssi:-65,numLevels:5,signalLevel:4
12-03 15:49:40.549340: E/WifiManager(812): calculateSignalLevel rssi:-61,numLevels:5,signalLevel:4
12-03 15:49:43.553364: E/WifiManager(812): calculateSignalLevel rssi:-61,numLevels:5,signalLevel:4
12-03 15:49:46.569255: E/WifiManager(812): calculateSignalLevel rssi:-56,numLevels:5,signalLevel:4
12-03 15:49:49.574200: E/WifiManager(812): calculateSignalLevel rssi:-56,numLevels:5,signalLevel:4
12-03 15:49:52.582927: E/WifiManager(812): calculateSignalLevel rssi:-58,numLevels:5,signalLevel:4
12-03 15:49:55.588845: E/WifiManager(812): calculateSignalLevel rssi:-58,numLevels:5,signalLevel:4
12-03 15:49:58.592169: E/WifiManager(812): calculateSignalLevel rssi:-55,numLevels:5,signalLevel:4
12-03 15:50:01.596349: E/WifiManager(812): calculateSignalLevel rssi:-55,numLevels:5,signalLevel:4
12-03 15:50:04.619143: E/WifiManager(812): calculateSignalLevel rssi:-49,numLevels:5,signalLevel:4
以上log确认当前wifi连接正常，并通过下面log进行确认（搜索getActivityNetworkInfo进行确认）
Line 22: 12-03 15:49:27.901477 812 1197 D ConnectivityService: getActiveNetworkInfo:NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "Huawei-Guest", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false, simId: 0/10102
Line 23: 12-03 15:49:27.902108 812 1142 D ConnectivityService: getActiveNetworkInfo:NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "Huawei-Guest", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false, simId: 0/10102
Line 24: 12-03 15:49:27.903662 812 24894 D ConnectivityService: getActiveNetworkInfo:NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "Huawei-Guest", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false, simId: 0/10102
Line 25: 12-03 15:49:27.904284 812 827 D ConnectivityService: getActiveNetworkInfo:NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "Huawei-Guest", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false, simId: 0/10102
Line 27: 12-03 15:49:27.922907 812 822 D ConnectivityService: getActiveNetworkInfo:NetworkInfo: type: WIFI[], state: CONNECTED/CONNECTED, reason: (unspecified), extra: "Huawei-Guest", roaming: false, failover: false, isAvailable: true, isConnectedToProvisioningNetwork: false, simId: 0/10102
。。。。
在通过搜索Posix，并找到对应的应用，log如下：
Line 16856: 12-03 15:50:14.670167 1752 12457 D Posix : [Posix_connect Debug]Process com.huawei.android.hwouc :82
在找到当前log上下文中类似下面log中的信息，如下：
12-03 15:50:14.754620 1752 12457 I System.out: [socket][26:35765] exception
12-03 15:50:14.754672 1752 12457 I System.out: [CDS]close[35765]
12-03 15:50:14.756266 1752 12457 I System.out: close [socket][/0.0.0.0:35765]
通过以上log确认，虽让当前wifi连接正常，但是连接服务器时抛出异常。这个时候我们使用网络封包分析工具Wireshark进行分析，通过搜索上面蓝色端口号
35765，得到以下信息如下：
157 33.913491 192.168.61.185 111.206.10.11 TCP 76
35765→82 [SYN] Seq=0 Win=65535 Len=0 MSS=1460 SACK_PERM=1 TSval=2602632 TSecr=0 WS=64
158 33.997772 111.206.10.11 192.168.61.185 ICMP 104 Destination unreachable (Host administratively prohibited)
这个信息表示对方主机不存在或者没有跟对方建立连接
因此最后得到确认，服务器不可达，此时排除手机端问题，也就是说当前wifi连接ok，但是无法连接服务器，需要check服务器事是否稳定。